[Bug bootstrap/54304] linking stage picks up system mpfr instead of in-tree version

[tobi at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54304

--- Comment #7 from Tobias Schlüter <tobi at gcc dot gnu.org> 2012-08-17 
19:35:30 UTC ---
Ok, the one in ~/usr/lib is 2.2.1, so this error wouldn't appear if it got
picked up.